Vacuum pump drive



July 1957 R. K. EVANS 7 2,798,662

: VACUUM-PUMP DRIVE Filed Dec. 26, 1952 l 67 1% I V V g I 5 2/ l l Z l l Ln 1 Inventor fan 1025 V Attorneys United States Patent i VACUUM PUMP DRIVE Ronald K. Evans, Birmingham, Mich, assignor to General Motors Corporation, Detroit, Micln, a corporation of Delaware Application December 26, 1952, Serial N 0. 328,031 9 Claims. (Cl. 230-462) This invention relates to internal combustion engines, and more particularly, to their accessory pump mountings and drive mechanisms.

The invention is particularly directed to a motor vehicle diesel engine and to a simplified mounting and drive for the accessory vacuum pump of such an engine. Motor vehicles, especially trucks and buses, may have various vacuum-operated units such as brakes and windshield wipers, and the production of vacuum/to operate these units is a simple matter when the vehicles are equipped with Otto engines as the intake manifold of an Otto engine may be used as a vacuum source but an accessory vacuum pump is necessary for vacuum production in diesel engine equipped motor vehicles.

It is an object of the invention to provide an internal combustion engine with an engine driven pump so located as to be readily accessible.

Another object of the invention is to relocate the accessory vacuum pump of a diesel engine from the normal accessory drive portion of the engine to the cylinder head cover of the engine so that more room for the remaining accessories at the normal accessory drive location is had.

Further objects of the invention are to relocate the vacuum pump of'a diesel engine to the cylinder head cover of the engine so that the pump is readily accessible and so that the drive and mounting therefor are of great simplicity.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred form of the persent invention is clearly shown.

The drawing is a transverse section through the cylinder head portion of a two-stroke cycle diesel engine illustrating the novel association of the vacuum pump therewith.

The engine is the well known General Motors Series 51 model and therefore only those portions of the engine directly concerned with the present invention are shown. A double-acting vacuum pump 10 is secured to the upper surface of the cylinder head cover 12 by screws 14, and the cover 12 is secured to the upper surface of the cylinder head 16 by a pair of upwardly projecting cylinder head studs 18 and cylinder head cover cap screws 29 (only one stud and cap screw being visible as the section is perpendicular the axis of the engine). A fuel injector 22 is secured in a vertical bore in the cylinder head 16 by a seat clamp 24. The fuel injector 22 is of known design and includes a nozzle portion 26 to inject fuel into the combustion chamber and an internal plunger (not shown) actuated by reciprocation of a pump push rod 28. The upper push rod 30 of the engine projects through a passage 32 in the cylinder head 16 and is pivotably secured to the fuel injector rocker arm 34 by a clevis 36. The rocker arm 34 is pivotably mounted on a shaft 38 which is supported on the cylinder head 16 by a bracket 40. The push rod 30 is reciprocated in the usual manner by the cam shaft (not shown) of the engine Patented July 9, 1957 ice to. oscillate the rocker arm 34 and thereby actuate the reciprocable rod 28 of the fuel injector 22. The forenoted description, excluding reference to the vacuum pump 10, was concerned with known engine construction and therefore is presented only as an aid in understanding the novel vacuum pump arrangement.

The vacuum pump 10 includes an upper casting 41 and a lower casting 42 having a flexible diaphragm 44 secured between them by the screws 14 to form an annular upper pumping chamber 46 and an annular lower pumping, chamber 48. Flexing of the diaphragm 44 for alternate enlargement and contraction of the chambers is accomplished by reciprocation of a push rod 50 pivotably engaged at its ball-shaped lower end by the spherical bottom of a socket 52 formed in the rocker arm 34 near the connection 54 between the rocker arm and push rod 30. The push rod 50 passes through an air seal 56 and is provided with a shoulder 58 that engages the lower diaphragm protector disk 60. A compression spring 62 in the upper chamber 46 bears against the upper diaphragm protector disk 64 through a washer 66. The push rod 50 provides a positive upward pumping stroke while the downward return stroke is provided by the coil spring 62. The vacuum pump 10 is preferably arranged for double-acting two-stage or series operation as shown, although it may be arranged for double-acting or parallel operation if desired. The lower pumping chamber 48 is provided with an intake check valve 68 and an exhaust check valve 70, and the upper pumping chamber 46 is provided with intake and exhaust check valves '72 and 74. The valves are identical and include valve disks '76 lightly biased against the valve seats 78 by springs 80. The intake passage 82 of the lower pumping chamber 48 is suitably connected to the vacuum reservoir (not shown) of the motor vehicle. The exhaust passage '84 of the lower pumping chamber 48 serves as the intake passage for the upper pumping chamber 46, thereby placing the pumping chambers in two-stage relation, the upper pumping chamber 46 emptying to atmosphere through an exhaust passage 88.

The lower pumping chamber 48 is preferably provided with less clearance volume than the upper pumping chamber 46 so that the volumetric efliciency of the initial stage of the pump is greater than the volumetric efiiciency of the final pumping stage. Providing the initial pumping stage with a higher volumetric efiiciency than the final pumping stage results in higher vacuum production in the initial or lower pumping chamber 48 than in the final or upper pumping chamber 46 without the use of a differential area piston. The high vacuum or initial pumpin-g stage is preferably arranged as shown so that differential pressure on the flexible diaphragm will augment the force of the return spring 62 thereby enabling the use of a relatively light return spring.

The pump may be adapted for parallel operation if desired by inverting the valves 72 and 74, by utilizing the passage 88 as an intake passage in parallel with intake passage 82, and by venting passage 84 to atmosphere so that it will exhaust both pumping chambers.

While the preferred embodiment of the invention has been described fully in order to explain the principles of the invention, it is to be understood that modifications in structure may be made by the exercise of skill in the art within the scope of the invention, which is not to be regarded as limited by the detailed description of the preferred embodiment.

I claim:

1. A pumping system adapted for operation from the cylinder head rocker arm of an internal combustion engine of the type having a cam shaft comprising, in combination, a cylinder head, a rocker arm pivotally secured to said cylinder head, a push rod adapted for reciprocation by the cam shaft of said engine, said push rod being operatively engaged with said arm to oscillate the same, a device for introducing fluid to said engine includinga rod reciprocable in said head operatively engaged with said arm for actuation thereby, a cover secured to said head to enclose said arm, a reciprocating accessory pump secured to said cover, and a pump actuating push rod operatively engaged with said pump and extending through said cover and operatively engaging said arm for reciprocation thereby.

2. A pumping system adapted for operation from the cylinder head rocker arm of a diesel engine of the type having a cam shaft comprising, in combination, a cylinder head, a rocker arm pivotably secured to said cylinder head, a push rod adapted for reciprocation by the cam shaft of. said engine, said push rod being pivotably engaged with said arm to oscillate the same, a device for introducing fluid to said engine including a rod reciproca ble in said head operatively engaged with said arm for actuation thereby, a cover secured to said head to enclose said arm, a reciprocating accessory pump secured to Said cover, and a pump actuating push rod operatively engaged with said pump and extending through said cover and operatively engaging said arm for reciprocation thereby.

3. A pumping system adapted for operation from the cylinder head rocker arm of a diesel engine of the type having a cam shaft comprising, in combination, a cylinder head, a rocker arrn pivotably secured to said cylinder head, a push rod adapted for reciprocation by the cam shaft of said engine, said push rod being pivotably engaged with said arm to oscillate the same, a fuel injector secured to said head operatively engaged with said arm for actuation thereby, and a reciprocating accessory pump secured to said head operatively engaged with said arm separately of said fuel injector for actuation by said arm.

4. A vacuum pumping system adapted for operation from the cylinder head rocker arm of a diesel engine of the type having a cam shaft comprising, in combination, a cylinder head, a rocker arm pivotably secured to said cylinder head, a push rod extending through said head adapted for reciprocation by the cam shaft of said engine, said push rod being pivotably engaged with said arm to oscillate the same, a fuel injector secured to said head operatively engaged with said arm for actuation thereby, a cover secured to said head to enclose said arm, a vacuum pump mounted on said cover including a movable wall and a spring urging said Wall in one direction, a passage through said cover, and a pump push rod extending through said passage operatively engaging said Wall and said arm for reciprocation by said arm, said arm serving to move said wall against said spring.

5. A vacuum pumping system adapted for operation from the cylinder head rocker arm of a diesel engine of the type having a cam shaft comprising, in combination, a cylinder head, a rocker arm pivotably secured to said cylinder head, a push rod extending through said head adapted for reciprocation by the cam shaft of said engine, said push rod being pivotably secured to said arm to oscillate the same, a fuel injector secured to said head operatively engaged with said arm for actuation thereby, a cover secured to said head to enclose said arm, a double-acting vacuum pump mounted on said cover including a movable Wall and a spring urging said wall in one direction, said pump having one pumping chamber on from the cylinder head rocker arm of a diesel engine of the type having a cam shaft comprising, in combination, a cylinder head, a rocker arm pivotably secured to said cylinder head, a push rod extending through said head adapted for reciprocation by the cam shaft of said engine, said push rod being pivotably secured to said arm to oscillate the same, a fuel injector secured to said head operatively engaged with said arm for actuation thereby, a cover secured to said head to enclose said arm, a doubleacting vacuum pump outside said cover and secured thereto including a flexible diaphragm and a spring urging said diaphragm in one direction, said pump having a first stage pumping chamber on one side of said diaphragm and a second stage pumping chamber on the other side of said diaphragm, a passage through said cover, and a pump push rod extending through said passage operatively engaging said diaphragm and said arm for reciprocation by said arm, said arm serving to flex said diaphragm for the intake stroke of the first stage pumping chamber and said spring serving to flex said diaphragm for the intake stroke of the second stage pumping chamber.

7. A vacuum pumping system adapted for operation from the cylinder head rocker arm of a diesel engine of the type having a cam shaft comprising, in combination a cylinder head, a rocker arm pivotably secured to said cylinder head, a push rod extending through said headadapted for reciprocation by the cam shaft of said engine, said push rod being pivotably engaged with said aim to oscillate the same, a fuel injector secured to said head operatively engaged with said arm for actuation thereby, a cover secured to said head to enclose said arm, a vacuum pump outside said cover and secured thereto including a movable wall and a spring urging said wall in one direction, a passage through said cover, and a pump push rod extending through said passage operatively engaging said wall and said arm for reciprocation by said arm, said arm serving to move said wall against said spring, a socket formed in said arm proximate said first mentioned push rod connection with said arm and being in substantial alignment with said first mentioned push rod, said pump push rod being pivotably received in said socket.

8. A pumping system adapted for operation from the cylinder head rocker arm of an internal combustion engine of the type having a cam shaft comprising, in combination, a cylinder head, a rocker arm pivotably secured to said cylinder head, a push rod adapted for reciprocation by the cam shaft of said engine, said push rod being pivotably engaged with said arm to oscillate the same, a fuel injector rod reciprocable in said head operatively engaged with said arm for actuation thereby, a cover secured to said head to enclose said arm, a pump secured to said cover including a movable wall and a spring urging said Wall in one direction, and a pump push rod extending through said cover and operatively engaging said wall and said arm for reciprocation by said arm, said arm serving to move said Wall against said spring, a socket formed in said arm proximate said first mentioned push rod con nection with said arm and being in substantial alignment with said first mentioned push rod, said pump push rod being pivotably received in said socket.

9. A vacuum pumping system adapted for operation from the cylinder head rocker arm of a diesel engine of the type having a cam shaft comprising, in combination, a cylinder head, a rocker arm pivotably secured to said cylinder head, a push rod extending through said head adapted for reciprocation by the cam shaft of said engine, said push rod being pivotably secured to said arm to oscillate the same, a fuel injector secured to said head operatively engaged with said arm for actuation thereby, a cover secured to said head to enclose said arm, a doubleacting vacuum pump outside said cover and secured there to including a flexible diaphragm and a spring urging said diaphragm in one direction, said pump having a first stage pu p g h mber on one side of said diaphragm and a second stage pumping chamber on the other side of said diaphragm, a passage through said cover, and a pump push rod extending through said passage operatively engaging saiddiaphragm and said arm for reciprocation by said arm, said arm serving to flex said diaphragm for the intake stroke of the first stage pumping chamber and said spring serving to flex said diaphragm for the intake stroke of the second stage pumping chamber, a socket formed in said arm proximate to said first mentioned push rod connection with said arm and being in substantial alignment With said first said mentioned push rod, said pump push rod being pivotably received in said socket.

References (fired in the file of this patent UNITED STATES PATENTS 

